For the sake of accuracy, the software behind Stack Overflow is not called StackExchange. "StackExchange" is the hosted version of the Stack Overflow software, available to the public as a paid service to build your own site. Stack Overflow was the original and built from the ground up using these components: meta.stackexchange.com/questions/10369/…
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Robert Cartaino♦Oct 11 '09 at 18:59